Re: [PATCH 0/2] Export kdump crashkernel CMA ranges

[Sourabh Jain <sourabhjain@linux.ibm.com>]

Cc others who can provide input.

On 03/11/25 09:28, Sourabh Jain wrote:
> /sys/kernel/kexec_crash_cma_ranges to export all CMA regions reserved
> for the crashkernel to user-space. This enables user-space tools
> configuring kdump to determine the amount of memory reserved for the
> crashkernel. When CMA is used for crashkernel allocation, tools can use
> this information to warn users that attempting to capture user pages
> while CMA reservation is active may lead to unreliable or incomplete
> dump capture.
>
> While adding documentation for the new sysfs interface, I realized that
> there was no ABI document for the existing kexec and kdump sysfs
> interfaces, so I added one.
>
> The first patch adds the ABI documentation for the existing kexec and
> kdump sysfs interfaces, and the second patch adds the
> /sys/kernel/kexec_crash_cma_ranges sysfs interface along with its
> corresponding ABI documentation.
>
> *Seeking opinions*
> There are already four kexec/kdump sysfs entries under /sys/kernel/,
> and this patch series adds one more. Should we consider moving them to
> a separate directory, such as /sys/kernel/kexec, to avoid polluting
> /sys/kernel/? For backward compatibility, we can create symlinks at
> the old locations for sometime and remove them in the future.
>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Baoquan he <bhe@redhat.com>
> Cc: Jiri Bohac <jbohac@suse.cz>
> Cc: Shivang Upadhyay <shivangu@linux.ibm.com>
> Cc: linuxppc-dev@lists.ozlabs.org
> Cc: kexec@lists.infradead.org
>
> Sourabh Jain (2):
>    Documentation/ABI: add kexec and kdump sysfs interface
>    crash: export crashkernel CMA reservation to userspace
>
>   .../ABI/testing/sysfs-kernel-kexec-kdump      | 53 +++++++++++++++++++
>   kernel/ksysfs.c                               | 17 ++++++
>   2 files changed, 70 insertions(+)
>   create mode 100644 Documentation/ABI/testing/sysfs-kernel-kexec-kdump
>